// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
// This tests the vtkCenterOfMass class.

#include <vtkCenterOfMass.h>
#include <vtkDoubleArray.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkSmartPointer.h>

#include <cmath>
#include <limits>

template <class A>
bool fuzzyCompare1D(A a, A b)
{
  return std::abs(a - b) < std::numeric_limits<A>::epsilon();
}

template <class A>
bool fuzzyCompare3D(A a[3], A b[3])
{
  return fuzzyCompare1D(a[0], b[0]) && fuzzyCompare1D(a[1], b[1]) && fuzzyCompare1D(a[2], b[2]);
}

int TestCenterOfMass(int, char*[])
{
  // Create a point set of a square
  vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
  points->InsertNextPoint(0, 0, 0);
  points->InsertNextPoint(1, 0, 0);
  points->InsertNextPoint(0, 1, 0);
  points->InsertNextPoint(1, 1, 0);

  vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();
  polydata->SetPoints(points);

  // Compute the center of mass
  vtkSmartPointer<vtkCenterOfMass> centerOfMassFilter = vtkSmartPointer<vtkCenterOfMass>::New();
  centerOfMassFilter->SetInputData(polydata);

  // Test unweighted
  {
    centerOfMassFilter->SetUseScalarsAsWeights(false);
    centerOfMassFilter->Update();

    double center[3];
    centerOfMassFilter->GetCenter(center);

    double correct[3] = { 0.5, 0.5, 0 };
    if (!fuzzyCompare3D(center, correct))
    {
      std::cerr << "Error: center is " << center[0] << " " << center[1] << " " << center[2]
                << " but should be " << correct[0] << " " << correct[1] << " " << center[2]
                << std::endl;
      return EXIT_FAILURE;
    }
  }

  // Test weighted
  {
    centerOfMassFilter->SetUseScalarsAsWeights(true);

    vtkSmartPointer<vtkDoubleArray> weights = vtkSmartPointer<vtkDoubleArray>::New();
    weights->SetNumberOfValues(4);
    weights->SetValue(0, 1);
    weights->SetValue(1, 1);
    weights->SetValue(2, 1);
    weights->SetValue(3, 2);

    polydata->GetPointData()->SetScalars(weights);

    centerOfMassFilter->Update();

    double center[3];
    centerOfMassFilter->GetCenter(center);

    double correct[3] = { 0.6, 0.6, 0 };
    if (!fuzzyCompare3D(center, correct))
    {
      std::cerr << "Error: center is " << center[0] << " " << center[1] << " " << center[2]
                << " but should be " << correct[0] << " " << correct[1] << " " << center[2]
                << std::endl;
      return EXIT_FAILURE;
    }
  }

  return EXIT_SUCCESS;
}
